思路
\(KD-tree\)模板题
代码
#include<cstdio>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<queue>
#include<vector>
#include<ctime>
using namespace std;
typedef long long ll;
#define ls TR[rt].ch[0]
#define rs TR[rt].ch[1]
const int N = 1000000 + 100,INF = 1e9;
ll read() {
ll x=0,f=1;char c=getchar();
while(c<'0'||c>'9') {
if(c=='-') f=-1;
c=getchar();
}
while(c>='0'&&c<='9') {
x=x*10+c-'0';
c=getchar();
}
return x*f;
}
struct node {
int ch[2],d[2],mx[2],mn[2];
}TR[N],TMP,a[N];
int n,m;
int ans,root;
int fx;
bool cmp(const node &A,const node &B) {
return A.d[fx] < B.d[fx];
}
void up(int rt) {
for(int i = 0;i <= 1;++i) {
if(ls) TR[rt].mn[i] = min(TR[rt].mn[i],TR[ls].mn[i]),
TR[rt].mx[i] = max(TR[rt].mx[i],TR[ls].mx[i]);
if(rs) TR[rt].mn[i] = min(TR[rt].mn[i],TR[rs].mn[i]),
TR[rt].mx[i] = max(TR[rt].mx[i],TR[rs].mx[i]);
}
}
int build(int l,int r,int now) {
fx = now;
int mid = (l + r) >> 1;
nth_element(a + l,a + mid,a + r + 1,cmp);
TR[mid] = a[mid];
int rt = mid;
for(int i = 0;i <= 1;++i) TR[mid].mn[i] = TR[mid].mx[i] = TR[mid].d[i];
if(l < mid) ls = build(l,mid - 1,now ^ 1);
if(r > mid) rs = build(mid + 1,r,now ^ 1);
up(mid);
return mid;
}
void insert(int rt,int now) {
if(TMP.d[now] >= TR[rt].d[now]) {
if(rs) insert(rs,now ^ 1);
else {
rs = ++n;
TR[n] = TMP;
for(int i = 0;i <= 1;++i) TR[n].mn[i] = TR[n].mx[i] = TR[n].d[i];
}
}
else {
if(ls) insert(ls,now ^ 1);
else {
ls = ++n;
TR[n] = TMP;
for(int i = 0;i <= 1;++i) TR[n].mn[i] = TR[n].mx[i] = TR[n].d[i];
}
}
up(rt);
}
int dis(const node &A,const node &B) {
return abs(A.d[0] - B.d[0]) + abs(A.d[1] - B.d[1]);
}
int get(node A,node B) {
int ret = 0;
for(int i = 0;i <= 1;++i) ret += max(0,A.mn[i] - B.d[i]);
for(int i = 0;i <= 1;++i) ret += max(0,B.d[i] - A.mx[i]);
return ret;
}
void query(int rt,int now) {
int d = dis(TR[rt],TMP),dl = INF,dr = INF;
ans = min(ans,d);
if(ls) dl = get(TR[ls],TMP);
if(rs) dr = get(TR[rs],TMP);
if(dl < dr) {
if(dl < ans) query(ls,now ^ 1);
if(dr < ans) query(rs,now ^ 1);
}
else {
if(dr < ans) query(rs,now ^ 1);
if(dl < ans) query(ls,now ^ 1);
}
}
int Query(int x,int y) {
TMP.d[0] = x;TMP.d[1] = y;
ans = INF;
query(root,0);
return ans;
}
void Insert(int x,int y) {
TMP.d[0] = x;TMP.d[1] = y;
insert(root,0);
}
int main() {
// freopen("2648/17.in","r",stdin);
n = read(),m = read();
for(int i = 1;i <= n;++i) {
a[i].d[0] = read();a[i].d[1] = read();
}
root = build(1,n,0);
for(int i = 1;i <= m;++i) {
int opt = read(),x = read(),y = read();
if(opt == 1) Insert(x,y);
else printf("%d\n",Query(x,y));
}
return 0;
}